Understanding the Arc Flash Requirements

Free Arc Hazard Assessment Tool:

It is important to perform an on-site assessment of your work place to evaluate potential hazards. In order to determine if the proper clothing is worn you should calculate your potential thermal hazard. This hazard can be compared with the ATPV shown on all garments meeting ASTM F1506. You must match the ATPV of the garment to the potential.

We have made available for downloading the Duke Heat Flux Calculator and the Users Guide to assist you in using the calculator.

Alliance Suppliers, Inc(ASI) is a supplier of a very high quality line of arc protective clothing. We are not an electrical safety consultant. We have made the above information available to you as a free resource. ASI is not responsible for the use or misuse of this program.

Protection From Electric Arc Exposure:

The intense energy and very short duration of an electric arc flash represents a very unique exposure. Every work clothes made from regular cotton or poly/cotton fabrics, regardless of weight, can be readily ignited at some exposure level and will continue to burn adding to the extent of injury sustained from the arc alone. NFPA70E now requires employees to wear flame resistant (FR) protective clothing that meets the requirements of ASTM F1506 wherever there is possible exposure to an electric arc flash. It requires employers to perform a flash hazard analysis to determine the flash protection boundary distance.

The standard is designed to protect employees working inside these flash protection boundaries by requiring protective clothing for the corresponding Hazard/Risk Category that has an ATPV of at least the value listed in the “Protective Clothing Characteristics” section of the standard (see below). OSHA has confirmed that garments which meet the requirements of ASTM F1506 are in compliance with OSHA 29 CFR 1910.269 Electrical Power Generation, Transmission and Distribution, with regard to garments not contributing to burn severity.

Typical Protective Clothing Systems
Table 130.7(C)(11) Protective Clothing Characteristics
HAZARD RISK CATEGORY CLOTHING DESCRIPTION
(Typical Number of Clothing Layers in Parentheses)
MINIMUM ATPV RATING OF PPE cal/cm2
0
Non-melting, flammable materials 4.5 oz.(1)
N/A
1
FR Shirt and FR Pants(1)
4
2
Cotton Underware Plus FR Shirt and FR Pants(2)
8
3
Cotton Underware Plus FR Shirt and FR Pants Plus FR Coverall (3)
25
4
Cotton Underware Plus FR Shirt and FR Pants Plus Double Layer Switching Coat and Pants(3)
40

NEPA 70 E Requirements:

The National Fire Protection Association (NFPA) published the latest edition of the NFPA 70E Standard (Standard for Electrical Safety Requirement for Employee Workplaces) in 2004. The revised version requires employees to wear flame resistant (FR) protective clothing that meets the requirements of ASTM F1506 wherever there is possible exposure to an electric arc flash. It requires employers to perform a flash hazard analysis to determine the flash protection boundary distance. The standard is designed to protect employees working inside these flash protection boundaries by requiring protective clothing for corresponding Hazard/Risk Category that has an arc thermal performance value (ATPV) of at least the value listed in the “Protective Clothing Characteristics” section of the standard (see table above). The vast majority of major companies in the U.S. have some employees who work on near energized electrical conductors or circuit parts. In addition, the Department of Energy has required that federal and contractor employees comply with NFPA 70E and the 2002 National Electric Code (NEC) references the NEPA 70E standard. Finally, OSHA considers the NFPA 70E standard a “recognized industry practice.”

When incident energy exceeds 40 cal/cm2 at the working distance, greater emphasis than normal should be placed on de-energizing before working on or near the exposed electrical conductors or circuit parts.

NFPA 70E: 3 Ways to Analyze the Arc Flash Hazard:

A Flash Hazard Analysis will determine the flash protection boundary and the personal protective equipment that people within the flash protection boundary should use. There are three ways provided within NFPA 70E to perform a Flash Hazard Analysis to determine the required performance level of protective clothing for the corresponding Hazard Risk Category, which are highlighted below.

  1. Detailed Flash Hazard Analysis

    There are multiple tools available to the industry to help perform a Flash Hazard Analysis on energized equipment. Where it has been determined that a person will be working within the flash protection boundary, the flash hazard analysis shall determine, and the employer shall document, the incident energy exposure of the worker (in calories per square centimeter). The determination of the incident energy can be performed using multiple tools:

    • NFPA 70E Equations (Examples given in 70E; Annex D)
    • ArcPro (Kinectrics)
    • IEEE 1584
    • SKM Power Tools
    After the incident energy has been determined and documented, the proper fabric for the protective clothing can be selected.
  2. NFPA 70E Hazard/risk Category Classifications Or Job Task Matrix

    The second way to perform a hazard risk assessment is using the Hazard/Risk Category Classifications of job Task Matrix provided in NFPA 70E. Below are excerpts of the most common job tasks and the corresponding Hazard Risk Category:

  3. ANNEX H Simplified; Two Category, Flame-resistant (FR) Clothing Approach
    The use of table H.1 is suggested as a simplified approach to ensure adequate PPE for electrical workers within facilities with large and diverse electrical systems. The clothing listed fulfils the minimum FR clothing requirements of the NFPA 70E Table 130.7 © (10) and 130.7 © (11).
Table H.1 Simplified, Two -category, Flame-Resistant Clothing System
CLOTHING* APPLICATION TASKS

Everyday Work Clothing
ATPV ≥8
Note: INDURA Ultra Soft Style 301 7 oz. =8.7
INDURA Ultra Soft Style 451 9 oz. =12.4

All Hazard/Risk Category 1 and 2 tasks listed in table 130.7 (c) (10)
On system operating at less tha 1,000 volts, these task include work on all equipment, except insertion/removal of low voltage motor starter"buckets,";insertion/removal of power circuit breakers from switchgear cubicles or removal of bolted covers from switchgear.
On systems operating at 1,000 volts or greater,tasks also include the operation of switching devices with equipment enclosure doors closed.

Electrical "Switching" Clothing
ATPV ≥40
Note: INDURA Ultra Soft two layer options available >40

All Hazard/Risk Category 3 and 4 tasks listed in table 130.7 (c) (10). On operating systems operating at 1,000 volts or greater, these tasks include work on exposed live parts of all equipment.
On systems of less than 1,000 volts, tasks include insertion/removal of low voltage motor starter MCC"buckets," insertion/removal of power circuit breakers and removal of bolted covers from switchgear.


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